"As prime minister, she helped restore the confidence and pride that has always been the hallmark of Britain at its best.

"And as an unapologetic supporter of our transatlantic alliance, she knew that with strength and resolve we could win the Cold War and extend freedom’s promise.

Obama added: "Here in America, many of us will never forget her standing shoulder to shoulder with President Reagan, reminding the world that we are not simply carried along by the currents of history—we can shape them with moral conviction, unyielding courage and iron will.

"Michelle and I send our thoughts to the Thatcher family and all the British people as we carry on the work to which she dedicated her life—free peoples standing together, determined to write our own destiny."

Thatcher died after a stroke this morning, following years spent in an increasingly fragile state.